OBSERVATIONS / RECOLLECTIONS / STORIES

Not With a Bang

To me, the appeal isn’t the gung ho action — the alien invasion/interstellar war/space opera stuff — although some of that is great fun.

Nor is it the softer, more philosophical side of the genre — tales about time travel, alternate universes, artificial intelligence, or the imagined technology of future societies — all of which can be fascinating and thought-provoking.

No, what I really dig is the science in science fiction. The science that, wearing the mantle of fiction, is really pondering and trying to make sense of — well — life, the universe, and everything.

I dig the science because I think science is the most important, most valuable attribute of the human species. Science doesn’t profess to be the Undisputed Truth. It is merely the best guess of our best minds, based on what we know at the moment.

And crucially, science is happy to reach new conclusions based on new evidence.

Consider this example: a cosmic year is the time it takes a star to complete one revolution around the center of its galaxy. For us Earthlings, one cosmic year is somewhere between 225,000 and 250,000 earth years.

That’s based on the estimated size of the Milky Way Galaxy (diameter of about 100,000 light years) and the estimated speed of the Sun as we zip through space (around 515,000 mph).

At the moment, 225,000-250,000 years is about as precise as we can get. But, as new evidence refines the number up or down, science will be cool with that.

Likewise, if space aliens showed up, claimed that they put us here in the distant past, and presented irrefutable proof of that claim, science would be cool with that, too.

The rest of society probably would not. Typically, outside the disciplines of genuine science, minds are not open to new information and a new conclusion — not if it runs counter to preconceived notions.

Which is why I firmly believe that science equals real knowledge and real understanding, and everything else is just blather.

I was a journalism major, not a math or physics person, and it shows. I struggle to understand Einstein. I labor through books by Steven Hawking. When Michio Kaku comes on TV to explain a bit of theoretical physics, I may or may not get it.

But, even though I am woefully unprepared, I’m still deeply curious. I want to understand the big picture. I mean, what is this cosmos thing really all about, anyway?

Well, consider the scientific thinking of the moment.

The Beginning

Science believes that about 13.7 billion years ago, at the literal beginning of the universe, nothing existed except a Singularity.

The Singularity was a point of super-intense gravity. It was infinitely dense, infinitely hot, and infinitesimally small. Where this theoretical something came from, we don’t know.

Nor do we know why it suddenly exploded/inflated in a cataclysm — the Big Bang — that generated space, time, and all of the energy and matter in the universe.

As the cataclysm expanded, pockets of basic elements (hydrogen, helium, lithium) became more and more dense. Stars ignited, galaxies formed.

Elements of all kinds were flung out into space. Some of this “star stuff,” as the late Carl Sagan called it, collected and coalesced and became the building blocks of new stars and their planets.

All of us, and all things around us, are made of elements created out there somewhere, inside the furnaces of stars. That process continued today.

The Present

So here we are, 13.7 billion years later, somewhere in the universe, on board Planet Earth. If we could get a bird’s-eye view of the entire cosmos, what would it look like, and where inside it are we?

Science says that the universe is still expanding from the Big Bang, and it is populated by gazillions of stars, all in motion.

When stars get close enough to be gravitationally attracted, they form into galaxies — swirling masses that may contain billions of stars each.

Our star, the Sun, is inside the Milky Way Galaxy, which is made up of some 200-400 billion stars.

The name Milky Way comes from its appearance from Earth as a faint band of light across the night sky. We see it as a band because the galaxy is disc-shaped, and we see it edge-on. We see the glow of multitudes of stars.

The Sun is located in one of the spiral arms of the Milky Way, about 30,000 light years from the galactic core.

The cosmos is so vast that our puny minds can’t truly comprehend it. But we can try to get oriented.

Because interstellar distances get huge fast, science expresses distance in light years. One light year is the distance light travels in one year.

The speed of light is 186,282 miles per second. If you do the math, one light year equals about 6 trillion miles.

Light from the Moon takes 1.3 seconds to reach the Earth.

Light from the Sun takes eight minutes to reach the Earth.

Light from Proxima Centauri, the nearest star beyond the Sun, takes 4.3 years to reach the Earth.

Light takes 100,000 years to cross the Milky Way Galaxy from edge to edge.

Looking outward from the Milky Way, we see other galaxies — and galactic groups — and clusters and superclusters of galactic groups. In all directions are galaxies by the billions.

The immediate galactic neighborhood of the Milky Way consists of 30-50 galaxies (depending on who’s counting) called the Local Group. Most of these galaxies are gravitationally connected to the two most massive members, the Milky Way and the Andromeda Galaxy.

Drawing of the Local Group of galaxies. Note the white bar (top) that denotes a distance of one million light years. Also shown is the Triangulum Galaxy, the third largest galaxy in the group.

To get a handle on the scale of things, consider an analogy used by NASA astronomer Sten Odenwald.

A penny is about one inch in diameter. Odenwald points out that if the Milky Way were the size of a penny, the Andromeda Galaxy would be about 23 inches away.

The Virgo cluster, a separate group of galaxies beyond the Local Group, would be 50 feet from the penny.

The most distant galaxies detected by the Hubble Space Telescope would be about 20 miles from the Milky Way “penny.”

Essentially, that is the edge of the observable universe. The light from galaxies beyond that point has not yet reached us.

No matter which direction we look in space, we see clusters and superclusters of galaxies, all moving away from us. As hard as it is to grasp, the experts say that the universe is expanding in all directions, has no center, and would look the same to any observer anywhere.

Image from the Hubble Space Telescope showing one tiny wedge of the visible universe. This image, a mere pinhole view, depicts about .002 percent of the panorama in all directions. You’re looking at about 1,500 galaxies.

The Future

So science believes that the universe began with a bang, and matter and energy spread, and life appeared, and we humans evolved to the point of our present awareness.

Being a curious lot, we want to know what will become of us, our planet, our star, and ultimately, the cosmos itself.

For years, scientists debated whether the universe will keep expanding indefinitely (an open universe) or eventually will slow down and re-collapse into a “Big Crunch” (a closed universe).

The answer, they now believe, is open.

Most speculation ended during the 1990s, when evidence mounted that the universe will not re-collapse — cannot re-collapse — because the expansion of the cosmos actually is accelerating.

The evidence of which I speak comes from deep in the realm of theoretical physics.

According to Einstein’s equation E = mc2, the mass of a body is a measure of its energy content. But when the equation is used to calculate how much matter the universe should contain, only four percent of it can be found. Where is the missing matter?

Furthermore, by the law of gravity, large objects such as galaxy clusters should attract each other, and their gravity should pull in other objects. However, most galaxy clusters are moving apart and accelerating to boot. Why isn’t gravity getting the job done?

New theories about dark matter and dark energy are trying to answer those questions.

Dark matter is a theoretical form of matter that for the moment is undetectable, but whose presence can be inferred from its gravitational effects. Theoretically, the missing 96 percent of matter could exist in the form of dark matter.

Dark energy is a theoretical force that repels — the opposite of the force of gravity, which attracts. If dark energy exists, and if it outweighs gravity, it could account for the accelerated expansion of the universe.

The study of these theories and others will occupy science for a long time. But the latest evidence is compelling that the universe will continue to expand.

That being the case, what, in the long run, will happen?

— About 1.5 million years from now, the sun will burn up the last of its hydrogen. It will expand in size beyond the orbit of Venus and become a red giant.

At that stage, the Sun will begin to burn its helium until that, too, is gone. In a series of bursts, the outer layers of the Sun will fly off into space. The remaining core will be a white dwarf, an Earth-sized chunk of carbon and oxygen.

— About 2.5 million years from now, the Milky Way and Andromeda galaxies will begin to collide.

— About 100 billion years from now, the galaxies of the Local Group will have sped away into space, and the Milky Way will be alone.

— About a trillion years from now, all of the stars in the Milky Way will have exhausted their fuel and cooled to cinders. Only white dwarfs, neutron stars, and black holes will remain.

Neutron stars are remnants of collapsed stars composed almost entirely of neutrons. In that state, they are relatively stable. But eventually, they will collapse further and become black holes.

Black holes are objects so dense that nothing, not even light, can escape. They grow by glomming up nearby mass and retaining it.

But one theory says that a few particles can, in fact, escape near the very edge (the event horizon) of a black hole. Thus, even black holes eventually will decay and vanish, too.

— About 100 trillion years from now, the universe will be nearly inert. The only energy remaining will be from protons decaying into subatomic particles.

— About a zillion years from now (or some other crazy number), the last black holes will have evaporated, and all of the protons will have decayed. Only scattered electrons and random bits of cold, inert matter will remain.

And that, as they say, will be that.

That timeline may prove to be accurate, or it may wildly miss the mark. Regardless, it will be adjusted, amended, and changed freely as new evidence is found.

Science will be cool with that.

A composite by the California Institute of Technology of the entire sky in infrared, showing the distribution of galaxies beyond the Milky Way (shown at center). Blue indicates the nearest galaxies, green sources are at moderate distances, and red sources are the most distant.